Regeneration of zeolites used for purifying 1,1,1,2-tetrafluoroethane

Abstract

1,1,1,2-Tetrafluoroethane (R134a) is purified to remove 50-10,000 wt. ppm of 2-chloro-1,1-difluoroethylene (R1122) by contacting with a zeolite or carbon molecular sieve having an average pore diameter of 3.8 to 4.8 Angstroms. The zeolite or carbon molecular sieve is regenerated by inert gas stripping residual R134a, followed by a regeneration at elevated temperatures using an inert gas. Regeneration of the zeolite or carbon molecular sieve is accomplished without the substantial reduction in capacity for impurities.

I claim: 
     
       1. A method for regenerating zeolites or carbon molecular sieves used for removing 2-chloro-1,1-difluoroethylene (R1122) from 1,1,1,2-tetrafluoroethane (R134a) comprising: (a) removing R134a by stripping the zeolite or carbon molecular sieve with an inert gas at a temperature of about 0° to 60° C. and a pressure not higher than about 300 kPa;   (b) separating and recovering R134a from the inert gas   (c) removing R1122 from said zeolite by passing an inert gas over said zeolite or carbon molecular sieve at a temperature of about 150° to 300° C. and a pressure no higher than about 300 kPa.   
     
     
       2. The process of claim 1 wherein said inert gas of (a) is at least one member of the group consisting of nitrogen, argon, helium, carbon dioxide and low boiling fluorocarbons. 
     
     
       3. The process of claim 2 wherein said inert gas of (a) is nitrogen. 
     
     
       4. The process of claim 1 wherein said inert gas of (a) is air. 
     
     
       5. The process of claim 2 wherein said inert gas of (a) is R113. 
     
     
       6. The process of claim 1 wherein said inert gas of (c) is at least one member of the group consisting of nitrogen, argon, helium, carbon dioxide and low boiling fluorocarbons. 
     
     
       7. The process of claim 6 wherein said inert gas of (c) is nitrogen. 
     
     
       8. The process of claim 1 wherein said inert gas of (c) is air. 
     
     
       9. The process of claim 4 wherein said inert gas of (c) is R113. 
     
     
       10. The process of claim 1 wherein the pressure is no higher than about 100 kPa. 
     
     
       11. The process of claim 1 wherein said zeolite is calcium chabazite. 
     
     
       12. A process for purification of 1,1,1,2-tetrafluoroethane (R134a) by removing 2-chloro-1,1-difluoroethylene (R1122) by contacting said R134a with a zeolite or carbon molecular sieve wherein the improvement comprises regenerating said zeolite by a sequence of steps comprising: (a) removing R134a by stripping the zeolite or carbon molecular sieve with an inert gas at a temperature of 0° to 60° C. and a pressure of no higher than about 300 kPa;   (b) separating from the inert gas of (a) the R-134a and returning the separated R134a to the purification process;   (c) removing R1122 from said zeolite by passing an inert gas over said zeolite or carbon molecular sieve at a temperature of about 150° to 300° C. and a pressure of less than about 300 kPa; and,   (d) disposing of the R1122.   
     
     
       13. The process of claim 12 wherein said inert gas of (a) is at least one member of the group consisting of nitrogen, argon, helium, carbon dioxide and low boiling fluorocarbons. 
     
     
       14. The process of claim 13 wherein said inert gas of (a) is nitrogen. 
     
     
       15. The process of claim 12 wherein said inert gas is air. 
     
     
       16. The process of claim 13 wherein said inert gas is R113. 
     
     
       17. The process of claim 12 wherein said inert gas of (c) is at least one member of the group consisting of nitrogen, argon, helium, carbon dioxide and low boiling fluorocarbons. 
     
     
       18. The process of claim 17 wherein said inert gas of (c) is nitrogen. 
     
     
       19. The process of claim 12 wherein said zeolite is calcium chabazite. 
     
     
       20. The process of claim 12 wherein the pressure is no higher than about 100 kPa.